Six series of tests on a large centrifuge, including 50 models of shallow foundations supporting shear walls, were performed to study the nonlinear load-deformation characteristics of shallow foundations during cyclic and earthquake loading. Rocking of the footing during cyclic loading progressively rounds the foundation soil, and this rounding causes a reduction in contact area between the footing and soil thereby causing a nonlinearity and stiffness reduction on the moment-rotation relationship. Analytical modeling was carried out to model the moment-rotation behavior of footing-soil interface. The rigid footing and the soil beneath were modeled as a single element that captures the essential features of the moment-rotation behavior that were observed in the centrifuge experiments.